Cell Size as a Determinant of the Clone-Forming Ability of Human Keratinocytes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 82; no. 16; pp. 5390 - 5394
• Main Authors: Barrandon, Yann, Green, Howard
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.08.1985; National Acad Sciences
• Subjects: 3T3 cells; Animal cells; Biological and medical sciences; Cell cultures. Hybridization. Fusion; Cell Division; Cell growth; Cells; Cells, Cultured; Cellular differentiation; Clone Cells; Cultured cells; Epidermal cells; Epidermis; Fundamental and applied biological sciences. Psychology; Humans; Infant, Newborn; Inoculation; Keratinocytes; Keratins; Kinetics; Male; Molecular and cellular biology; Probability; Skin - cytology; Stem cells; Time Factors; Human; Cell proliferation; Cell culture; Regulation(control); Size; Keratinocyte; Cell differentiation
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.82.16.5390

Keratinocytes isolated from human epidermis and subsequently cultured may form clones if they are 11 μ m or less in diameter but are irreversibly committed to further enlargement and terminal differentiation if they are 12 μ m or more in diameter. When a founding cell of 11 μ m or less forms a small rapidly growing clone in culture, the cells of that clone are able to found new colonies even when their diameter is as great as 20 μ m. As the clone becomes larger and grows more slowly, the maximal size of its clonogenic cells is reduced toward that of the epidermis. A cultured cell of up to 20 μ m in diameter can, when it divides, give rise to clonogenic progeny smaller than itself, thus reversing the process of enlargement. Cells larger than 20 μ m cannot divide and therefore cannot be rescued from terminal differentiation. It is concluded that when keratinocytes multiply rapidly, they extend reversibly the maximal size at which they are capable of generating clones into the range usually characteristic of terminally differentiating cells. It is proposed that this mechanism enables the keratinocyte to accommodate an increased rate of multiplication to its need to attain a large size during terminal differentiation.